The present invention relates to semiconductor devices using a photoresist, and to processes for manufacturing the same.
Various types of photoresists have been used or proposed. These resists should have a variety of desirable characteristics or properties. In general, all or most of these resists generally demand etching resistance, adhesiveness with low light absorption at 193 nm wavelength for ArF. Additionally, the resists should be developable by using 2.38 wt % aqueous tetramethylammonium hydroxide (TMAH) solution. It is, however, difficult to synthesize a polymer satisfying one or all these properties.
Many researches have focused on studies on norbolac type resin as a resin to increase transparency at 193 nm wavelength and increase etching resistance. As merely an example, xe2x80x9cBell Labsxe2x80x9d tried to introduce alicyclic unit to the backbone chain of a copolymer in order to enhance etching resistance. A copolymer resin in which the backbone chain has norbornene, acrylate and maleic anhydride substituent, as represented by chemical formula I has been suggested:
[Formula I] See Appendix A
In the polymer resin of formula I, the maleic anhydride portion (portion A) was used for polymerizing alicyclic olefin group.
The maleic anhydride portion is soluble in 2.38% aqueous TMAH solution even it is not exposed, and thus a y-portion having tert-butyl substituent should be highly increased in order to prevent dissolution. But increase of the y-portion causes relative decrease of z portion, which enhances sensitivity and adhesiveness with substrate, to cause disadvantage in that photoresist is removed from the wafer in practical patterning.
Thus, an effective pattern cannot be formed without separately using a solubility controlling agent, and even if a pattern is formed by using a solubility controlling agent, the adhesiveness is too poor to be applied to practical patterning.
Under such circumstances, Bell Labs tried to solve the above-mentioned problems by using a solubility controlling agent of cholesterol type and by employing two-component resist comprising a polymer of cyclo-olefin and maleic anhydride.
However, in this case, very large amount (about 30% by weight based on the polymer) of the solubility controlling agent should be used, and thus the polymer of the above molecular structure basically has too low reproducibility and too high cost to be used as a polymer for a photoresist. From the above, it is seen that an improved photoresist resin that is cost effective, easy to manufacture, and has desirable other properties is clearly desired.
The present inventors have performed intensive studies to overcome the above limitations encountered in conventional resins, and as a result, they could synthesize novel norbornene derivatives having hydrophilic group(s). In a specific embodiment, the present invention provides a method using a step of introducing the monomer to the backbone chain of the polymer to develop a polymer having excellent resolution due to prominent enhancement of adhesive strength by introducing a hydrophilic group (xe2x80x94OH). The present method yields a photoresist having excellent etching resistance and heat resistance which are the characteristics of alicyclic olefins.
Numerous benefits or advantages are achieved by way of the present invention over conventional techniques. In a specific embodiment, the present invention provides a monomer comprising a novel norbornene derivative represented by following formula II:
[Formula II] See Appendix A
wherein, Rxe2x80x2 and Rxe2x80x3 independently represent hydrogen, or linear or branched C1-C4 alkyl group with or without substituent(s), m represents number of 1 to 8, and n represents number of 1 to 6, and a process for preparing the same.
In an alternative embodiment, the present invention provides a polymer for a photoresist comprising bicycloalkene compounds represented by chemical formulas II and V, and maleic anhydride of chemical formula VI, and a process for preparing the same.
In a further embodiment, the present invention provides a polymer for photoresist represented by formula III or IV, which comprises bicycloalkene compound(s) and maleic anhydride, and process for preparing the same.
[Formula III] See Appendix A
[Formula IV] See Appendix A
In the formula, Rxe2x80x2 and Rxe2x80x3 independently represent hydrogen, or linear or branched C1-C4 alkyl group with or without substituent(s), R1 and R2 independently represent hydrogen, or linear or branched alkyl, cycloalkyl, alkoxyalkyl or cycloalkoxyalkyl having 1 to 10 carbon atoms with or without substituent(s), m is an integer from 1 to 8, and the molar ratio w:x:y:z is (0-99%):(0-99%):(0-99%) (0-99%) [provided that w and x are independently 0.005-0.9 part by mole, and y and z are independently 0.001-0.9 part by mole in case of formula IV].
In still a further embodiment, the present invention provides a polymer for photoresist which comprises bicycloalkene compounds represented by formulas II and V, and maleic anhydride represented by formula VI, and a photoresist formed by using a polymer represented by formula III, IV, VII, VIII or IX, and a process for manufacturing the photoresist.
[Formula V] See Appendix A
[Formula VI] See Appendix A
Still further, the present invention provides a polymer for photoresist. The polymer includes a variety of elements such as bicycloalkene compounds represented by formulas II and V, and maleic anhydride represented by formula VI, and a process for forming a photoresist pattern by the use of the photoresist formed with the polymer represented by formula III, IV, VII, VIII or IX.
Moreover, the present invention provides a polymer for photoresist. The present polymer includes a variety of elements such as bicycloalkene compounds represented by formulas II and V, and maleic anhydride represented by formula VI, and a semiconductor device using the photoresist formed with the polymer represented by formula III, IV, VII, VIII or IX.
[Formula VII] See Appendix A
[Formula VIII] See Appendix A
[Formula IX] See Appendix A